Well, rings are tricky because size-metric parts in Tokais-. I would guess they are Gotoh made parts.Just measure then and check for some same size rings. I can say you Goldo rings don not fit (slightly bigger) and vintage size ones like Gil Yaron replicas for example are very slightly smaller (barely notices however). I would go for Montreaux ones but they are expensive. Contact Philadelphia Luthiers and check for proper size ones.
Rings crack because they are not CAB made and are not flexible so try curved ones.
I had that issue in a LS-70 2001 made.
Good luck.